i2c-algo-pca: Rework waiting for a free bus
[linux-2.6.git] / drivers / i2c / algos / i2c-algo-pca.c
1 /*
2  *  i2c-algo-pca.c i2c driver algorithms for PCA9564 adapters
3  *    Copyright (C) 2004 Arcom Control Systems
4  *    Copyright (C) 2008 Pengutronix
5  *
6  *  This program is free software; you can redistribute it and/or modify
7  *  it under the terms of the GNU General Public License as published by
8  *  the Free Software Foundation; either version 2 of the License, or
9  *  (at your option) any later version.
10  *
11  *  This program is distributed in the hope that it will be useful,
12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  *  GNU General Public License for more details.
15  *
16  *  You should have received a copy of the GNU General Public License
17  *  along with this program; if not, write to the Free Software
18  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19  */
20
21 #include <linux/kernel.h>
22 #include <linux/module.h>
23 #include <linux/moduleparam.h>
24 #include <linux/delay.h>
25 #include <linux/jiffies.h>
26 #include <linux/init.h>
27 #include <linux/errno.h>
28 #include <linux/i2c.h>
29 #include <linux/i2c-algo-pca.h>
30
31 #define DEB1(fmt, args...) do { if (i2c_debug >= 1)                     \
32                                  printk(KERN_DEBUG fmt, ## args); } while (0)
33 #define DEB2(fmt, args...) do { if (i2c_debug >= 2)                     \
34                                  printk(KERN_DEBUG fmt, ## args); } while (0)
35 #define DEB3(fmt, args...) do { if (i2c_debug >= 3)                     \
36                                  printk(KERN_DEBUG fmt, ## args); } while (0)
37
38 static int i2c_debug;
39
40 #define pca_outw(adap, reg, val) adap->write_byte(adap->data, reg, val)
41 #define pca_inw(adap, reg) adap->read_byte(adap->data, reg)
42
43 #define pca_status(adap) pca_inw(adap, I2C_PCA_STA)
44 #define pca_clock(adap) adap->i2c_clock
45 #define pca_set_con(adap, val) pca_outw(adap, I2C_PCA_CON, val)
46 #define pca_get_con(adap) pca_inw(adap, I2C_PCA_CON)
47 #define pca_wait(adap) adap->wait_for_completion(adap->data)
48 #define pca_reset(adap) adap->reset_chip(adap->data)
49
50 static void pca9665_reset(void *pd)
51 {
52         struct i2c_algo_pca_data *adap = pd;
53         pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_IPRESET);
54         pca_outw(adap, I2C_PCA_IND, 0xA5);
55         pca_outw(adap, I2C_PCA_IND, 0x5A);
56 }
57
58 /*
59  * Generate a start condition on the i2c bus.
60  *
61  * returns after the start condition has occurred
62  */
63 static void pca_start(struct i2c_algo_pca_data *adap)
64 {
65         int sta = pca_get_con(adap);
66         DEB2("=== START\n");
67         sta |= I2C_PCA_CON_STA;
68         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
69         pca_set_con(adap, sta);
70         pca_wait(adap);
71 }
72
73 /*
74  * Generate a repeated start condition on the i2c bus
75  *
76  * return after the repeated start condition has occurred
77  */
78 static void pca_repeated_start(struct i2c_algo_pca_data *adap)
79 {
80         int sta = pca_get_con(adap);
81         DEB2("=== REPEATED START\n");
82         sta |= I2C_PCA_CON_STA;
83         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
84         pca_set_con(adap, sta);
85         pca_wait(adap);
86 }
87
88 /*
89  * Generate a stop condition on the i2c bus
90  *
91  * returns after the stop condition has been generated
92  *
93  * STOPs do not generate an interrupt or set the SI flag, since the
94  * part returns the idle state (0xf8). Hence we don't need to
95  * pca_wait here.
96  */
97 static void pca_stop(struct i2c_algo_pca_data *adap)
98 {
99         int sta = pca_get_con(adap);
100         DEB2("=== STOP\n");
101         sta |= I2C_PCA_CON_STO;
102         sta &= ~(I2C_PCA_CON_STA|I2C_PCA_CON_SI);
103         pca_set_con(adap, sta);
104 }
105
106 /*
107  * Send the slave address and R/W bit
108  *
109  * returns after the address has been sent
110  */
111 static void pca_address(struct i2c_algo_pca_data *adap,
112                         struct i2c_msg *msg)
113 {
114         int sta = pca_get_con(adap);
115         int addr;
116
117         addr = ( (0x7f & msg->addr) << 1 );
118         if (msg->flags & I2C_M_RD )
119                 addr |= 1;
120         DEB2("=== SLAVE ADDRESS %#04x+%c=%#04x\n",
121              msg->addr, msg->flags & I2C_M_RD ? 'R' : 'W', addr);
122
123         pca_outw(adap, I2C_PCA_DAT, addr);
124
125         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
126         pca_set_con(adap, sta);
127
128         pca_wait(adap);
129 }
130
131 /*
132  * Transmit a byte.
133  *
134  * Returns after the byte has been transmitted
135  */
136 static void pca_tx_byte(struct i2c_algo_pca_data *adap,
137                         __u8 b)
138 {
139         int sta = pca_get_con(adap);
140         DEB2("=== WRITE %#04x\n", b);
141         pca_outw(adap, I2C_PCA_DAT, b);
142
143         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
144         pca_set_con(adap, sta);
145
146         pca_wait(adap);
147 }
148
149 /*
150  * Receive a byte
151  *
152  * returns immediately.
153  */
154 static void pca_rx_byte(struct i2c_algo_pca_data *adap,
155                         __u8 *b, int ack)
156 {
157         *b = pca_inw(adap, I2C_PCA_DAT);
158         DEB2("=== READ %#04x %s\n", *b, ack ? "ACK" : "NACK");
159 }
160
161 /*
162  * Setup ACK or NACK for next received byte and wait for it to arrive.
163  *
164  * Returns after next byte has arrived.
165  */
166 static void pca_rx_ack(struct i2c_algo_pca_data *adap,
167                        int ack)
168 {
169         int sta = pca_get_con(adap);
170
171         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI|I2C_PCA_CON_AA);
172
173         if ( ack )
174                 sta |= I2C_PCA_CON_AA;
175
176         pca_set_con(adap, sta);
177         pca_wait(adap);
178 }
179
180 static int pca_xfer(struct i2c_adapter *i2c_adap,
181                     struct i2c_msg *msgs,
182                     int num)
183 {
184         struct i2c_algo_pca_data *adap = i2c_adap->algo_data;
185         struct i2c_msg *msg = NULL;
186         int curmsg;
187         int numbytes = 0;
188         int state;
189         int ret;
190         unsigned long timeout = jiffies + i2c_adap->timeout;
191
192         while (pca_status(adap) != 0xf8) {
193                 if (time_before(jiffies, timeout)) {
194                         msleep(10);
195                 } else {
196                         dev_dbg(&i2c_adap->dev, "bus is not idle. status is "
197                                 "%#04x\n", state);
198                         return -EAGAIN;
199                 }
200         }
201
202         DEB1("{{{ XFER %d messages\n", num);
203
204         if (i2c_debug>=2) {
205                 for (curmsg = 0; curmsg < num; curmsg++) {
206                         int addr, i;
207                         msg = &msgs[curmsg];
208
209                         addr = (0x7f & msg->addr) ;
210
211                         if (msg->flags & I2C_M_RD )
212                                 printk(KERN_INFO "    [%02d] RD %d bytes from %#02x [%#02x, ...]\n",
213                                        curmsg, msg->len, addr, (addr<<1) | 1);
214                         else {
215                                 printk(KERN_INFO "    [%02d] WR %d bytes to %#02x [%#02x%s",
216                                        curmsg, msg->len, addr, addr<<1,
217                                        msg->len == 0 ? "" : ", ");
218                                 for(i=0; i < msg->len; i++)
219                                         printk("%#04x%s", msg->buf[i], i == msg->len - 1 ? "" : ", ");
220                                 printk("]\n");
221                         }
222                 }
223         }
224
225         curmsg = 0;
226         ret = -EREMOTEIO;
227         while (curmsg < num) {
228                 state = pca_status(adap);
229
230                 DEB3("STATE is 0x%02x\n", state);
231                 msg = &msgs[curmsg];
232
233                 switch (state) {
234                 case 0xf8: /* On reset or stop the bus is idle */
235                         pca_start(adap);
236                         break;
237
238                 case 0x08: /* A START condition has been transmitted */
239                 case 0x10: /* A repeated start condition has been transmitted */
240                         pca_address(adap, msg);
241                         break;
242
243                 case 0x18: /* SLA+W has been transmitted; ACK has been received */
244                 case 0x28: /* Data byte in I2CDAT has been transmitted; ACK has been received */
245                         if (numbytes < msg->len) {
246                                 pca_tx_byte(adap, msg->buf[numbytes]);
247                                 numbytes++;
248                                 break;
249                         }
250                         curmsg++; numbytes = 0;
251                         if (curmsg == num)
252                                 pca_stop(adap);
253                         else
254                                 pca_repeated_start(adap);
255                         break;
256
257                 case 0x20: /* SLA+W has been transmitted; NOT ACK has been received */
258                         DEB2("NOT ACK received after SLA+W\n");
259                         pca_stop(adap);
260                         goto out;
261
262                 case 0x40: /* SLA+R has been transmitted; ACK has been received */
263                         pca_rx_ack(adap, msg->len > 1);
264                         break;
265
266                 case 0x50: /* Data bytes has been received; ACK has been returned */
267                         if (numbytes < msg->len) {
268                                 pca_rx_byte(adap, &msg->buf[numbytes], 1);
269                                 numbytes++;
270                                 pca_rx_ack(adap, numbytes < msg->len - 1);
271                                 break;
272                         }
273                         curmsg++; numbytes = 0;
274                         if (curmsg == num)
275                                 pca_stop(adap);
276                         else
277                                 pca_repeated_start(adap);
278                         break;
279
280                 case 0x48: /* SLA+R has been transmitted; NOT ACK has been received */
281                         DEB2("NOT ACK received after SLA+R\n");
282                         pca_stop(adap);
283                         goto out;
284
285                 case 0x30: /* Data byte in I2CDAT has been transmitted; NOT ACK has been received */
286                         DEB2("NOT ACK received after data byte\n");
287                         goto out;
288
289                 case 0x38: /* Arbitration lost during SLA+W, SLA+R or data bytes */
290                         DEB2("Arbitration lost\n");
291                         goto out;
292
293                 case 0x58: /* Data byte has been received; NOT ACK has been returned */
294                         if ( numbytes == msg->len - 1 ) {
295                                 pca_rx_byte(adap, &msg->buf[numbytes], 0);
296                                 curmsg++; numbytes = 0;
297                                 if (curmsg == num)
298                                         pca_stop(adap);
299                                 else
300                                         pca_repeated_start(adap);
301                         } else {
302                                 DEB2("NOT ACK sent after data byte received. "
303                                      "Not final byte. numbytes %d. len %d\n",
304                                      numbytes, msg->len);
305                                 pca_stop(adap);
306                                 goto out;
307                         }
308                         break;
309                 case 0x70: /* Bus error - SDA stuck low */
310                         DEB2("BUS ERROR - SDA Stuck low\n");
311                         pca_reset(adap);
312                         goto out;
313                 case 0x90: /* Bus error - SCL stuck low */
314                         DEB2("BUS ERROR - SCL Stuck low\n");
315                         pca_reset(adap);
316                         goto out;
317                 case 0x00: /* Bus error during master or slave mode due to illegal START or STOP condition */
318                         DEB2("BUS ERROR - Illegal START or STOP\n");
319                         pca_reset(adap);
320                         goto out;
321                 default:
322                         dev_err(&i2c_adap->dev, "unhandled SIO state 0x%02x\n", state);
323                         break;
324                 }
325
326         }
327
328         ret = curmsg;
329  out:
330         DEB1("}}} transfered %d/%d messages. "
331              "status is %#04x. control is %#04x\n",
332              curmsg, num, pca_status(adap),
333              pca_get_con(adap));
334         return ret;
335 }
336
337 static u32 pca_func(struct i2c_adapter *adap)
338 {
339         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
340 }
341
342 static const struct i2c_algorithm pca_algo = {
343         .master_xfer    = pca_xfer,
344         .functionality  = pca_func,
345 };
346
347 static unsigned int pca_probe_chip(struct i2c_adapter *adap)
348 {
349         struct i2c_algo_pca_data *pca_data = adap->algo_data;
350         /* The trick here is to check if there is an indirect register
351          * available. If there is one, we will read the value we first
352          * wrote on I2C_PCA_IADR. Otherwise, we will read the last value
353          * we wrote on I2C_PCA_ADR
354          */
355         pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
356         pca_outw(pca_data, I2C_PCA_IND, 0xAA);
357         pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ITO);
358         pca_outw(pca_data, I2C_PCA_IND, 0x00);
359         pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
360         if (pca_inw(pca_data, I2C_PCA_IND) == 0xAA) {
361                 printk(KERN_INFO "%s: PCA9665 detected.\n", adap->name);
362                 return I2C_PCA_CHIP_9665;
363         } else {
364                 printk(KERN_INFO "%s: PCA9564 detected.\n", adap->name);
365                 return I2C_PCA_CHIP_9564;
366         }
367 }
368
369 static int pca_init(struct i2c_adapter *adap)
370 {
371         struct i2c_algo_pca_data *pca_data = adap->algo_data;
372
373         adap->algo = &pca_algo;
374
375         if (pca_probe_chip(adap) == I2C_PCA_CHIP_9564) {
376                 static int freqs[] = {330, 288, 217, 146, 88, 59, 44, 36};
377                 int clock;
378
379                 if (pca_data->i2c_clock > 7) {
380                         switch (pca_data->i2c_clock) {
381                         case 330000:
382                                 pca_data->i2c_clock = I2C_PCA_CON_330kHz;
383                                 break;
384                         case 288000:
385                                 pca_data->i2c_clock = I2C_PCA_CON_288kHz;
386                                 break;
387                         case 217000:
388                                 pca_data->i2c_clock = I2C_PCA_CON_217kHz;
389                                 break;
390                         case 146000:
391                                 pca_data->i2c_clock = I2C_PCA_CON_146kHz;
392                                 break;
393                         case 88000:
394                                 pca_data->i2c_clock = I2C_PCA_CON_88kHz;
395                                 break;
396                         case 59000:
397                                 pca_data->i2c_clock = I2C_PCA_CON_59kHz;
398                                 break;
399                         case 44000:
400                                 pca_data->i2c_clock = I2C_PCA_CON_44kHz;
401                                 break;
402                         case 36000:
403                                 pca_data->i2c_clock = I2C_PCA_CON_36kHz;
404                                 break;
405                         default:
406                                 printk(KERN_WARNING
407                                         "%s: Invalid I2C clock speed selected."
408                                         " Using default 59kHz.\n", adap->name);
409                         pca_data->i2c_clock = I2C_PCA_CON_59kHz;
410                         }
411                 } else {
412                         printk(KERN_WARNING "%s: "
413                                 "Choosing the clock frequency based on "
414                                 "index is deprecated."
415                                 " Use the nominal frequency.\n", adap->name);
416                 }
417
418                 pca_reset(pca_data);
419
420                 clock = pca_clock(pca_data);
421                 printk(KERN_INFO "%s: Clock frequency is %dkHz\n",
422                      adap->name, freqs[clock]);
423
424                 pca_set_con(pca_data, I2C_PCA_CON_ENSIO | clock);
425         } else {
426                 int clock;
427                 int mode;
428                 int tlow, thi;
429                 /* Values can be found on PCA9665 datasheet section 7.3.2.6 */
430                 int min_tlow, min_thi;
431                 /* These values are the maximum raise and fall values allowed
432                  * by the I2C operation mode (Standard, Fast or Fast+)
433                  * They are used (added) below to calculate the clock dividers
434                  * of PCA9665. Note that they are slightly different of the
435                  * real maximum, to allow the change on mode exactly on the
436                  * maximum clock rate for each mode
437                  */
438                 int raise_fall_time;
439
440                 struct i2c_algo_pca_data *pca_data = adap->algo_data;
441
442                 /* Ignore the reset function from the module,
443                  * we can use the parallel bus reset
444                  */
445                 pca_data->reset_chip = pca9665_reset;
446
447                 if (pca_data->i2c_clock > 1265800) {
448                         printk(KERN_WARNING "%s: I2C clock speed too high."
449                                 " Using 1265.8kHz.\n", adap->name);
450                         pca_data->i2c_clock = 1265800;
451                 }
452
453                 if (pca_data->i2c_clock < 60300) {
454                         printk(KERN_WARNING "%s: I2C clock speed too low."
455                                 " Using 60.3kHz.\n", adap->name);
456                         pca_data->i2c_clock = 60300;
457                 }
458
459                 /* To avoid integer overflow, use clock/100 for calculations */
460                 clock = pca_clock(pca_data) / 100;
461
462                 if (pca_data->i2c_clock > 10000) {
463                         mode = I2C_PCA_MODE_TURBO;
464                         min_tlow = 14;
465                         min_thi  = 5;
466                         raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */
467                 } else if (pca_data->i2c_clock > 4000) {
468                         mode = I2C_PCA_MODE_FASTP;
469                         min_tlow = 17;
470                         min_thi  = 9;
471                         raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */
472                 } else if (pca_data->i2c_clock > 1000) {
473                         mode = I2C_PCA_MODE_FAST;
474                         min_tlow = 44;
475                         min_thi  = 20;
476                         raise_fall_time = 58; /* Raise 29e-8s, Fall 29e-8s */
477                 } else {
478                         mode = I2C_PCA_MODE_STD;
479                         min_tlow = 157;
480                         min_thi  = 134;
481                         raise_fall_time = 127; /* Raise 29e-8s, Fall 98e-8s */
482                 }
483
484                 /* The minimum clock that respects the thi/tlow = 134/157 is
485                  * 64800 Hz. Below that, we have to fix the tlow to 255 and
486                  * calculate the thi factor.
487                  */
488                 if (clock < 648) {
489                         tlow = 255;
490                         thi = 1000000 - clock * raise_fall_time;
491                         thi /= (I2C_PCA_OSC_PER * clock) - tlow;
492                 } else {
493                         tlow = (1000000 - clock * raise_fall_time) * min_tlow;
494                         tlow /= I2C_PCA_OSC_PER * clock * (min_thi + min_tlow);
495                         thi = tlow * min_thi / min_tlow;
496                 }
497
498                 pca_reset(pca_data);
499
500                 printk(KERN_INFO
501                      "%s: Clock frequency is %dHz\n", adap->name, clock * 100);
502
503                 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IMODE);
504                 pca_outw(pca_data, I2C_PCA_IND, mode);
505                 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLL);
506                 pca_outw(pca_data, I2C_PCA_IND, tlow);
507                 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLH);
508                 pca_outw(pca_data, I2C_PCA_IND, thi);
509
510                 pca_set_con(pca_data, I2C_PCA_CON_ENSIO);
511         }
512         udelay(500); /* 500 us for oscilator to stabilise */
513
514         return 0;
515 }
516
517 /*
518  * registering functions to load algorithms at runtime
519  */
520 int i2c_pca_add_bus(struct i2c_adapter *adap)
521 {
522         int rval;
523
524         rval = pca_init(adap);
525         if (rval)
526                 return rval;
527
528         return i2c_add_adapter(adap);
529 }
530 EXPORT_SYMBOL(i2c_pca_add_bus);
531
532 int i2c_pca_add_numbered_bus(struct i2c_adapter *adap)
533 {
534         int rval;
535
536         rval = pca_init(adap);
537         if (rval)
538                 return rval;
539
540         return i2c_add_numbered_adapter(adap);
541 }
542 EXPORT_SYMBOL(i2c_pca_add_numbered_bus);
543
544 MODULE_AUTHOR("Ian Campbell <icampbell@arcom.com>, "
545         "Wolfram Sang <w.sang@pengutronix.de>");
546 MODULE_DESCRIPTION("I2C-Bus PCA9564/PCA9665 algorithm");
547 MODULE_LICENSE("GPL");
548
549 module_param(i2c_debug, int, 0);